Certain control systems utilize multiple inputs, either separately or together, to provide an output. This occurs, for example, in systems for controlling the position of an aircraft flight control surface. In the case of an aircraft control system, the inputs may include a manual or pilot input and automatic input, such as may be derived from the autopilot or a stability augmenting system. Alternatively, redundant inputs may be used so that, if there is a failure in one, the other can be used to control the position of the control surface without false input from the failed input. With multiple inputs, it is necessary to select which of the inputs, or how much of each input, is to be used. In other words, the authority which each of the inputs has over the output can be adjusted.